Method and apparatus for etching a structure in a plasma chamber

Abstract

A plasma processing apparatus includes a plasma reaction chamber in which a plasma is generated for processing. First and second electrodes are located in the chamber for generating the plasma. First and second RF power sources provide RF power to the first and second electrodes, respectively. The apparatus also includes first and second impedance matching circuits through which the RF power is respectively provided from the first and second RF power supplies to the first and second electrodes. A first plasma controller monitors plasma density and, in response thereto, adjusts the RF power supplied by the first RF power source to the first electrode to achieve a given plasma density. A second plasma controller monitors the ion energy of plasma species impinging on a semiconductor structure associated with the second electrode and, in response thereto, adjusts the RF power supplied by the second RF power source to the second electrode to achieve a given ion energy.

1. A method for performing plasma etching on a structure, comprising:
 establishing a plasma in a gaseous atmosphere that contacts a first electrode; 
 monitoring plasma density by measuring the resistive component of the plasma's impedance load, and adjusting an amount of RF power, from a first RF power supply, supplied to the first electrode to achieve a given plasma density; and 
 monitoring ion energy of plasma species impinging on a semiconductor structure associated with a second electrode and, in response thereto, adjusting an amount of RF power, from a second RF power supply, supplied to the second electrode to achieve a given ion energy. 
 
   
   
     2. The method of  claim 1  wherein said plasma is produced by capacitively coupling the RF power into a chamber. 
   
   
     3. The method of  claim 1  wherein the semiconductor structure is mounted on a second electrode. 
   
   
     4. The method of  claim 1  wherein the step of monitoring the plasma density includes measuring a resistive load experienced by a first RF power source that establishes the plasma. 
   
   
     5. The method of  claim 1  wherein the given plasma density that is achieved is a constant plasma density during an etching process. 
   
   
     6. The method of  claim 1  wherein the given in energy that is achieved is a constant ion energy during an etching process. 
   
   
     7. The method of  claim 5  wherein the given ion energy that is achieved is a constant ion energy during an etching process.